sibilate vs articulate

sibilate is not an adjective while articulate is an adjective.

Word	Noun	Adjective	Verb	Adverb
sibilate	No	No	Yes	No
articulate	No	Yes	Yes	No

As verbs, articulate is a hypernym of sibilate; that is, articulate is a word with a broader meaning than sibilate:

Other hypernyms of sibilate include enounce, enunciate, pronounce, say, sound out.

sibilate (adjective)	articulate (adjective)
	expressing yourself easily or characterized by clear expressive language
	consisting of segments held together by joints

sibilate (verb)	articulate (verb)
make a sharp hissing sound, as if to show disapproval	speak, pronounce, or utter in a certain way
express or utter with a hiss	express or state clearly
utter a sibilant	put into words or an expression
pronounce with an initial sibilant	provide with a joint
	unite by forming a joint or joints